Gas turbine systems are widely utilized in fields such as power generation. A conventional gas turbine system includes a compressor section, a combustor section, and a turbine section. The compressor section supplies compressed air to the combustor section, wherein the compressed air is mixed with fuel and burned, generating a hot gas. This hot gas is supplied to the turbine section, wherein energy is extracted from the hot gas to produce work.
During operation of the gas turbine system, various components and areas in the system are subjected to high temperature flows, which can cause the components and areas to fail. Since higher temperature flows generally result in increased performance, efficiency, and power output of the gas turbine system and are thus desired in the gas turbine system, the components and areas that are subjected to high temperature flows must be cooled to allow the gas turbine system to operate with flows at increased temperatures.
One example of an area that should be cooled is the wheel space of the turbine section. The wheel space is generally the area of the turbine section surrounding the turbine rotor wheels. As the temperature in the wheel space increases due to increased temperature of flows through the wheel space or due to increased ambient temperatures external to the gas turbine system, components in the wheel space, such as rotor and bucket assembly components, may be subject to thermal expansion. This thermal expansion may eventually cause the various components to rub or otherwise contact each other, potentially resulting in catastrophic damage to the components and to the gas turbine system.
Various strategies are known in the art for cooling the wheel space to prevent damage to the wheel space components. For example, one solution utilizes a portion of the air exiting the compressor section of the gas turbine system to cool the wheel space. Bores are created in the compressor discharge case, which defines and separates the compressor discharge plenum and the forward portion of the wheel space. The bores are then plugged with bore plugs. When the temperature in the wheel space approaches an unacceptably high temperature, the bore plugs are removed, and a portion of the air from the compressor section is provided through the bores to the wheel space, cooling the wheel space.
However, this strategy for cooling the wheel space has potential drawbacks. For example, after the bore plugs have been removed, they cannot be replaced until the gas turbine system has been completely shut down. Thus, air from the compressor section will be constantly supplied to the wheel space after the bore plugs are removed until the gas turbine is shut down. In many cases, however, the wheel space may not require this constant cooling. For example, in many cases, wheel space temperature variations are caused by variations in the ambient temperature external to the gas turbine system. When the ambient temperature is relatively hot, such as during the afternoon or during the summer months, the wheel space may require cooling, but when the ambient temperature is relatively cool, such as during the evening or during the winter months, the wheel space may not require cooling. Thus, after the bore plugs have been removed and when the ambient temperature is relatively cool, air from the compressor section is unnecessarily diverted to the wheel space. This unnecessary diversion of compressed air may result in losses in the power generation and efficiency of the gas turbine system.
Accordingly, an apparatus and method for providing cooling air to high temperature gas turbine system areas and components would be desired in the art. For example, an apparatus and method that provides cooling air to the areas and components only as required, such as during relatively higher temperature operating conditions, would be advantageous.